When you come to a household appliance store, the first thing that catches your eye is the appearance of the unit. Glossy shine, matte texture or patterned design create the first impression of quality. However, few people think about what is hidden under the decorative layer, and what specific components ensure the durability of the structure. Understanding what refrigerator bodies are made ofhelps not only to choose a reliable model, but also to properly care for it during operation.
A modern refrigerator is a complex engineering object, where each part performs its own function. The outer shell protects the insides from mechanical damage, moisture and temperature changes. It also serves as the basis for fastening the doors and installing the compressor. In this article we will analyze in detail the chemical composition and physical properties of materials used by leading manufacturers around the world.
It is important to note that production technologies are constantly being improved. What was the norm ten years ago may be considered outdated today. For example, stainless steel in its pure form is used less and less due to its high cost, giving way to composite solutions. Let's dive into the world of metallurgy and polymer chemistry to understand what exactly is in your kitchen.
Steel foundation: the main structural material
The basis for creating the external contour of almost any household refrigerator is sheet steel. This is not just metal, but a specially processed alloy with certain magnetic and strength characteristics. Most often, cold-rolled steel with a thickness of 0.5 to 0.8 millimeters is used. It is this parameter that determines how rigid the structure will be and whether it will be subject to deformation during transportation.
The key requirement for the material is its ability to withstand loads from the weight of the internal contents and the unit’s own weight. Sheet steel provides the necessary rigidity of the frame. If manufacturers used thinner metal, the walls could bend, which would lead to a violation of the tightness of the seals or even damage to the thermal insulation.
However, ordinary steel is susceptible to corrosion. To prevent rust, the metal is pre-treated. At the factory, the sheets are coated with a thin layer of zinc or special primers. This process is called galvanization, and it is critical to the service life of the equipment. Without such protection, even in a dry room, pockets of oxidation could appear on the surface.
Interestingly, different parts of the body can be made from steel of different grades. The side walls, which do not bear the main load, may be thinner than the top cover or bottom. The bottom, in turn, must support the weight of the compressor and condenser, which is why reinforced rolling is often used there. This differentiation allows you to optimize production costs without losing reliability.
Polymer solutions: plastic in refrigerator construction
Contrary to popular belief, plastic in refrigerators is used not only for internal shelves. Modern technologies make it possible to use high-strength polymers to create external panels. This is especially true for built-in equipment or models in the budget segment, where weight and cost play a decisive role. The main material here is ABS plastic or polypropylene.
The use of polymers has its advantages. Plastic is not subject to corrosion in principle, which makes it ideal for conditions of high humidity. In addition, it has better thermal insulation properties compared to metal. However, there are also disadvantages: plastic is less resistant to mechanical shocks and can scratch more than metal with a high-quality coating.
- 🔹 ABS plastic —an impact-resistant thermoplastic resin, often used for internal chambers and decorative inserts.
- 🔹 Polycarbonate —a transparent and very durable material used in designer models.
- 🔹 Foamed polystyrene —can be used as an additional layer of insulation in the walls of the case.
Some manufacturers are experimenting with composite materials, combining a metal base with polymer coating. This results in a surface that feels good to the touch like plastic but has the strength of metal. Such solutions can often be found in premium lines, where the tactile component and unique surface texture are important.
⚠️ Attention: When cleaning plastic body panels, you should absolutely not use abrasive sponges and acetone-based solvents. This can lead to irreversible clouding of the surface or the appearance of microcracks.
Coating technologies and decorative finishing
After the formation of the metal frame, the stage of creating the appearance begins. It is the coating that protects the steel from scratches, fading in the sun and household chemicals. The most common method is powder coating. A special powder is sprayed onto grounded metal and baked at high temperature, forming a monolithic polymer film.
Technology is used to imitate stainless steel lamination. A thin film with a metal pattern is glued onto the prepared metal sheet, which is coated with a protective varnish on top. This allows you to get the "inox" effect for a fraction of the cost of real stainless steel. However, such coatings require careful care, as they are easily damaged by sharp objects.
In the segment, tempered glass is used. Glass panels can be colored, mirrored or with a printed pattern. The glass is easy to clean and does not scratch, but it is fragile when subjected to pinpoint impacts. Also popular are coatings Anti-Fingerprint (anti-fingers), which repel fat and do not leave marks from touch.
| Type of coating | Scratch resistance | Difficulty of maintenance | Cost |
|---|---|---|---|
| Powder enamel | Average | Low | Budget |
| Stainless steel | High | High (visible streaks) | High |
| Tempered glass | Very high | Medium | Premium |
| Film (imitation) | Low | Low | Medium |
The choice of color also affects production technology. Dark colors, such as black or graphite, require better application as they will show any imperfections in the paint more easily. Light colors, especially white and “silver,” are the most popular and have been technologically developed over the years.
Internal structure: insulation and filling
Between the outer and inner walls of the refrigerator there is a space that is filled with a heat insulator. The quality of this layer determines how well the unit will keep the cold and how much electricity it will consume. The modern standard is polyurethane foam (PPU). This material foams directly inside the body, filling all voids and creating a monolithic layer.
The filling process occurs automatically. The inner chamber (often plastic) is inserted into the outer metal casing, and the liquid foam component is supplied into the gap under pressure. It instantly expands in volume 30-40 times and hardens, tightly gluing the inner and outer shells. This gives the structure additional rigidity.
Why is polyurethane foam better than mineral wool?
Polyurethane foam has a closed cellular structure, which prevents moisture absorption. Mineral wool can settle over time and lose its properties when wet, but polyurethane foam lasts for decades without changes.
An important aspect is the environmental friendliness of the foaming agents used. Previously, freons were used, which destroy the ozone layer, but modern factories have switched to cyclopentane and other safe gases. The thickness of the insulation layer varies from 3 to 6 centimeters depending on the energy efficiency class of the model.
The quality of foaming directly affects the noise level of operation. If voids or “sinks” remain in the insulation layer, vibration from the compressor is transmitted to the walls of the housing, causing humming. Therefore, filling density control is one of the most important tasks on the production line.
Internal chambers: metal or plastic?
The internal part of the refrigerator in contact with food is also part of the overall design. Historically, cameras were made of enameled metal. Enamel is a glass-like coating baked onto steel at about 800 degrees. It is inert, does not absorb odors and is easy to clean.
Today, most refrigerators have plastic interiors. This is due to cheaper production and the ability to create complex shapes without sharp corners where dirt could accumulate. Plastic is less fragile: if a heavy jar falls, the glass enamel can break off, exposing the metal, and the plastic will only be dented.
- 🔸 Enamel - durable, but afraid of shocks and chips.
- 🔸 Plastic - lightweight, does not rust, but can absorb the odors of oily food.
- 🔸 Stainless steel - used in professional equipment, hygienic, but expensive.
There is a myth that plastic is harmful to health. In fact, food-grade plastic used in refrigerators undergoes the strictest certification. It does not release toxins even at low temperatures. However enamel coating is considered more hygienic for long-term storage of products, since its microporous structure (at the molecular level) is less prone to bacterial growth than scratches on plastic.
⚠️ Attention: If you notice a chip in the enamel inside the refrigerator, it must be repaired immediately paint with special food enamel or varnish. Exposed metal will begin to rust from condensation, and rust can penetrate through the wall to the outside.
☑️ Checking the quality of the body when purchasing
Environmental friendliness and recycling of materials
The issue of recycling old equipment is becoming increasingly relevant. Since the refrigerator body is made up of different materials, recycling requires separation. The steel casing makes up the lion's share of the weight and is used for ferrous metal scrapping. This is a valuable raw material that is melted and reused.
Plastic parts and insulation are more difficult to recycle. Polyurethane foam is difficult to separate from metal without special equipment. Modern processing plants use d